The present invention relates to a cake filtration apparatus in a structural unit which comprises a plate filter, a filtering aid-dosing device which is provided with an agitator, and a pump, lines, and valves for supplying the slurry which is to be filtered and for withdrawing the filtrate; the plate filter includes a filter unit within a housing. The filter unit is formed by a stack of filter plates which are disposed on a shaft, and can be rotated about its vertically disposed central axis for centrifuging the filter cake. The housing supports at least a portion of the drive mechanism for rotating the filter unit, and is provided with connections for supplying the slurry and for withdrawing the filtrate. The housing is provided with a housing bottom and a tank or hood-like housing part which is secured thereon and contains the peripheral wall and the top wall. The housing bottom includes a bottom plate which is disposed within a stationary bottom ring. The bottom plate can be raised from a lower closed position, in which it is sealed relative to the bottom ring, into an open position for removal of the centrifuged filter cake.
Pursuant to one known cake filtration apparatus of the aforementioned general type (compare company publication "FILTER-O-MAT 65" of the firm Filtrox-Werk AG, St. Gallen; No. 119 4880), the operation for rotating the filter unit is effected from the bottom of the filter housing. The connections for supplying the slurry and for withdrawing the filtrate are located on the upper portion of the filter housing. To raise the bottom plate for the removal of the centrifuged filter cake, the entire filter unit, along with the bottom plate disposed on the bottom side thereof, are raised from the upper side of the filter housing by means of a spindle. This means that every time the plate filter is to be cleaned, an attendant must first climb onto the top of the plate filter housing, must undertake opening of the bottom plate at the same time that the filter unit is raised, and after conclusion of the cleaning process must again climb onto the housing of the plate filter and manually undertake lowering of the filter unit. This significantly complicates operation and servicing of the apparatus. In addition, with these tasks there exists periods of danger which cannot be overlooked. Furthermore, the necessity for raising the filter unit together with the bottom plate entails considerable structural expense. Finally, it is necessary with the heretofore known apparatuses, after the filter unit has been raised and the bottom plate has been opened, to engage a coupling provided between the drive motor for the slurry pump and the drive for rotating the filter unit. Aside from the fact that this represents an additional operation, the energy requirement for operation of the slurry pump and for drive of the filter unit for rotation is so different that the drive motor for the slurry pump must be unnecessarily large.
It is therefore an object of the present invention to substantially improve a cake filtration apparatus of the aforementioned general type, so that serviceability is improved, sources of danger during servicing of the apparatus are eliminated, and structural expense is significantly reduced.